Sharks are a kind of fish with a full cartilaginous skeleton. It has a streamlined body. Sharks have a covering of dermal denticles to protect their skin from damage. Shark teeth are prized by collectors for their beauty because they are the only surviving relics of ancient sharks that are now extinct. Sharks have a different reproductive strategy from most fish. Instead of producing huge numbers of eggs and fry. Sharks normally produce around a dozen pups. The Census of Marine Life group reveals that 70% of the world's oceans are shark-free. They have discovered that although many sharks live up to depths as low as 1,500 metres. In ancient Greece, it was forbidden to eat shark flesh at women's festivals. A popular myth is that sharks are immune to disease and cancer; however, this is untrue. There are both diseases and parasites that affect sharks. Every year 26 to 73 million sharks are killed in the commmercial and also for the recreation fishing. However in the past, sharks are killed just for the sport of landing a good fighting fish. They are commonly used in the seafood in Japan and Australia. Especially in Victoria sharks are use to make fish and chips.